128-Toxic Effect of Cadmium as Affected by Humic Acid on Lettuce (Lactuca sativa L.) and Antioxidant Changes .

Abstract

We studied the binding of Cd to humic acid. The influence of a Cd-humic complex on enzyme activities (superoxide dismutases, peroxidases), availability of Cd and biomass compared with the behavior of no treatment (control). It was examined through a hydroponics system in lettuce. Treatments were: control (no additions), humic acid (0, 100 and 1000 mg L-1), and Cd (0, 2 and 4 mg 1:1). Enzyme activities increased significantly with increasing rates of cadmium. A significant increase (P<0.05) in cadmium content of leaves result in a considerable decrease in the biomass (P<0.05). Based on these results, it can be concluded that the humic acid applied in the media led to a decrease in the metal adsorption with plant. This material can be used to reduce the availability and mobility of heavy metals in the soils, too.